1e2o
From Proteopedia
OCA (Talk | contribs)
(New page: 200px<br /><applet load="1e2o" size="450" color="white" frame="true" align="right" spinBox="true" caption="1e2o, resolution 3.00Å" /> '''CATALYTIC DOMAIN FRO...)
Next diff →
Revision as of 11:37, 20 November 2007
|
CATALYTIC DOMAIN FROM DIHYDROLIPOAMIDE SUCCINYLTRANSFERASE
Overview
The dihydrolipoamide succinyltransferase (E2o) component of the, 2-oxoglutarate dehydrogenase multienzyme complex is composed of 24, subunits arranged with 432 point group symmetry. The catalytic domain (CD), of the E2o component catalyzes the transfer of a succinyl group from the, S-succinyldihydrolipoyl moiety to coenzyme A. The crystal structure of the, Escherichia coli E2oCD has been solved to 3.0 A resolution using molecular, replacement phases derived from the structure of the catalytic domain from, the Azotobacter vinelandii dihydrolipoamide acetyltransferase (E2pCD). The, refined model of the E. coli E2oCD consists of residues 172 to 404 and has, an R-factor of 0.205 (Rfree=0.249) for 9696 reflections between 20.0 and, 3.0 A resolution. Although both E2oCD and E2pCD form 24mers, subtle, changes in the orientations of two helices in E2oCD increase the stability, of the E2oCD 24mer in comparison to the less stable A. vinelandii E2pCD, 24mer. Like E2pCD and chloramphenicol acetyltransferase (CAT), the active, site of E2oCD is located in the middle of a channel formed at the, interface between two 3-fold related subunits. Two of the active-site, residues (His375 and Thr323) have a similar orientation to their, counterparts in E2pCD and CAT. A third catalytic residue (Asp379) assumes, a conformation similar to the corresponding residue in E2pCD (Asn614), but, different from its counterpart in CAT (Asp199). Binding of the substrates, to E2oCD is proposed to induce a change in the conformation of Asp379, allowing this residue to form a salt bridge with Arg184 that is analogous, to that formed between Asp199 and Arg18 in CAT. Computer models of the, active site of E2o complexed with dihydrolipoamide and with coenzyme A led, to the identification of the probable succinyl-binding pocket. The, residues which form this pocket (Ser330, Ser333, and His348) are probably, responsible for E2o's substrate specificity.
About this Structure
1E2O is a Single protein structure of sequence from Escherichia coli with SO4 as ligand. Active as Dihydrolipoyllysine-residue succinyltransferase, with EC number 2.3.1.61 Full crystallographic information is available from OCA.
Reference
Crystal structure of the truncated cubic core component of the Escherichia coli 2-oxoglutarate dehydrogenase multienzyme complex., Knapp JE, Mitchell DT, Yazdi MA, Ernst SR, Reed LJ, Hackert ML, J Mol Biol. 1998 Jul 24;280(4):655-68. PMID:9677295
Page seeded by OCA on Tue Nov 20 13:45:01 2007
